Solo, male traveller going around in December during Christmas-New-years.
Here’s my plan:

Fly to Amsterdam on 21/12/2013. Stay there for 2 nights (21st, 22nd)
Early Morning (6.30 AM) train to Paris (reaches around 9.15 AM). Halt on 23, 24 and 25. Christmas eve at the Notre Dame! And a Christmas pic on top of the Eiffel Tower!
Overnight train to Venice. Stay for one day/night (26th)
Early morning train on the 27th from Venice to Rome. Stay in Rome for 4 days/3 nights (27, 28, 29, 30)! I should be covering Vatican and Florence in this too, hopefully.
Late evening flight to Barcelona from Rome on the 30th. Bienvenido a Espana!
Stay in Barcelona for 3 days/3 nights – 31 Dec, 1 and 2 Jan 2014! Welcoming 2014 the Spanish way (won’t be much different for me I guess…mostly involves me sleeping off 30 minutes midnight )
Fly home from Barcelona in the afternoon of the 2nd of Jan, 2014. There ends the great, long-awaited trip.

Would love some company in any of these places – especially Venice, Rome and Barcelona. Let me know if anyone’s going to be there during the same time!